1. Field of the Invention
This invention relates to a thermostat-controlled fluid regulation valve and a circuit for cooling an internal combustion engine and a system recirculating exhaust gases from this engine, comprising such a valve.
2. Description of the Related Art
This type of valve is used to distribute fluid entering the valve to different outlet channels as a function of the temperature of the inlet fluid, in many applications in the fluids domain, particularly for cooling internal combustion engines used in vehicles. Thus conventionally, a valve may be used on the upstream side of a radiator designed to dissipate excess heat in a cooling fluid from an engine to be cooled, to control cooling by the radiator of the fluid entering the valve when this fluid becomes hot, and to control faster cooling of the fluid by the radiator when the temperature of the inlet fluid increases above a given predefined threshold value. The valve is provided with a thermostat-controlled element containing an expendable material such as wax to control regulation of the fluid flow through the valve.
Furthermore, for reasons related to protection of the environment, thermal combustion engines are increasingly used in association with an “EGR” (Exhaust Gas Recirculation) system. This system is an antipollution device that injects a proportion of exhaust gases from the engine into the intake manifold of this engine, to reduce combustion temperature peaks and therefore the formation of nitrogen oxides. Before injecting exhaust gases into the engine intake manifold, they have to be cooled using a cooling fluid that advantageously circulates in the same circuit as the engine cooling circuit, particularly in the radiator designed to dissipate excess heat from the cooling fluid. When the engine starts, it is desirable that the cooling fluid should be cooled more intensively than during the rest of the running time of the engine so that the injected exhaust gases are as cold as possible, to avoid injecting exhaust gases significantly hotter than the engine intake manifold into the manifold and thus enable a more uniform increase in the engine temperature. The cooling fluid used in the EGR system may be regulated by a thermostat-controlled valve placed on the upstream side of the above-mentioned radiator.
However, the presence of two separate valves immediately on the upstream side of the radiator, namely the fluid regulation valve related to the thermal combustion engine and the fluid regulation valve related to the EGR system, introduces dimensional problems. Furthermore, it usually means that the radiator is oversized since in practice the radiator comprises a first part designed for heat exchange of the fluid from the engine and a second part designed for heat exchange of the fluid from the EGR system, each part of the radiator being sized independently of the other as a function of maximum cooling needs firstly for the engine to be cooled and secondly for the EGR system.